Dev Toolbar App API

The Astro Dev Toolbar App API allows you to create apps that can be used to extend the Astro Dev Toolbar. This allows you to add new features and integrations with third-party services.

Adding apps

Astro Integrations can add apps in the astro:config:setup hook using the addDevToolbarApp method.

This method takes an object with different properties to define the app:

/**
 * @type {() => import('astro').AstroIntegration}
 */
export default () => ({
  name: "my-integration",
  hooks: {
    "astro:config:setup": ({ addDevToolbarApp }) => {
      addDevToolbarApp({
        id: "my-app",
        name: "My App",
        icon: "<svg>...</svg>",
        entrypoint: "./my-app.js",
      });
    },
  },
});

`id`

A unique identifier for the app. This will be used to uniquely identify the app in hooks and events.

{
  id: 'my-app',
  // ...
}

`name`

The name of the app. This will be shown to users whenever the app needs to be referenced using a human-readable name.

{
  // ...
  name: 'My App',
  // ...
}

`icon`

The icon of the app. This will be used to display the app in the UI. This can either be an icon from the icon list, or a string containing the SVG markup of the icon.

{
  // ...
  icon: '<svg>...</svg>', // or, e.g. 'astro:logo'
  // ...
}

`entrypoint`

The path to the app’s entrypoint.

{
  // ...
  entrypoint: './my-app.js',
}

A Dev Toolbar App is a .js or .ts file that default exports an object with the following properties:

import { defineToolbarApp } from "astro/toolbar";

export default defineToolbarApp({
  init(canvas) {
    const text = document.createTextNode('Hello World!');
    canvas.appendChild(text);
  }
});

`init()`

Signature: init(canvas: ShadowRoot, app: ToolbarAppEventTarget, server: ToolbarServerHelpers) => void

This is the core part of the app. This function will be called when the app is loaded, which will either be when the browser is idle or when the user clicks on the app in the UI, depending on which one comes first.

The function receives three arguments:

`canvas`

A ShadowRoot that the app can use to render its UI. Every app receives its own dedicated ShadowRoot for rendering its UI. Additionally, the parent element is positioned using position: absolute; and as such, the app UI automatically won’t affect the layout of the page.

export default defineToolbarApp({
  init(canvas) {
    canvas.appendChild(document.createTextNode('Hello World!'))
  }
});

`app`

An EventTarget augmented with a few helpers that can be used to send and receive events from the Dev Toolbar, see the Client-side Events section for more information.

export default defineToolbarApp({
  init(canvas, app) {
    app.onAppToggled(({ state }) => {
      const text = document.createTextNode(
        `The app is now ${state ? "enabled" : "disabled"}!`,
      );
      canvas.appendChild(text);
    });
  },
});

`server`

An object that can be used to communicate with the server, see the Client-Server Communication section for more information.

export default defineToolbarApp({
  init(canvas, app, server) {
    server.send('my-message', { message: 'Hello!' });

    server.on('server-message', (data) => {
      console.log(data.message);
    });
  },
});

`beforeTogglingOff()`

Signature: beforeTogglingOff(canvas: ShadowRoot): boolean | void

This optional function will be called when the user clicks on the app icon in the UI to toggle off the app. This function can be used, for example, to perform cleanup operations, or to ask the user for confirmation before toggling off the app.

If a falsy value is returned, the toggling off will be cancelled and the app will stay enabled.

export default defineToolbarApp({
  // ...
  beforeTogglingOff() {
    const confirmation = window.confirm('Are you sure you want to disable this app?');
    return confirmation;
  }
});

canvas

The ShadowRoot of the app, can be used to render any UI needed before closing. Same as the canvas argument of the init function.

Client-side Events

In addition to the standard methods of an EventTarget (addEventListener, dispatchEvent, etc), the app object also has the following methods:

`onToggled()`

Signature: onToggled(callback: (options: {state: boolean})) => void

Registers a callback to be called when the user clicks on the app icon in the UI to toggle the app on or off.

app.onToggled((options) => {
  console.log(`The app is now ${options.state ? 'enabled' : 'disabled'}!`);
});

`onToolbarPlacementUpdated()`

Signature: onToolbarPlacementUpdated(callback: (options: {placement: 'bottom-left' | 'bottom-center' | 'bottom-right'})) => void

This event is fired when the user changes the placement of the Dev Toolbar. This can, for example, be used to reposition the app’s UI when the toolbar is moved.

app.onToolbarPlacementUpdated((options) => {
  console.log(`The toolbar is now placed at ${options.placement}!`);
});

`toggleState()`

Signature: toggleState(options: {state: boolean}) => void

Changes the state of the app. This can be used to enable or disable the app programmatically, for example, when the user clicks on a button in the app’s UI.

app.changeAppState({state: false});

`toggleNotification()`

Signature: toggleNotification(options: {state?: boolean, level?: 'error' | 'warning' | 'info'}) => void

Toggles a notification on the app icon. This can be used to inform the user that the app requires attention, or remove the current notification.

app.toggleNotification({
  state: true,
  level: 'warning',
});

`state: boolean`

Indicates whether or not the app has a notification for the user. When true, the app icon will be highlighted. Conversely, when false, the highlight will be removed. If this property is not specified, true will be assumed.

`level: 'error' | 'warning' | 'info'`

Indicates the level of the notification. This will be used to determine the color and shape (dark pink circle, gold triangle, or blue square) of the highlight on the app icon. If this property is not specified, 'error' will be assumed.

Client-Server Communication

Using Vite’s methods for client-server communication, Dev Toolbar Apps can communicate with the server and vice versa. In order to facilitate this, helper methods are provided both in the app (client) and your integration (server).

On the client

In your app, you can use the server object on the init() hook to send and receive messages from the server.

`send()`

Signature: send<T>(event: stringify, data: T) => void

Sends data to the server.

init(canvas, app, server) {
  server.send('my-app:my-message', { message: 'Hello!' });
}

When sending messages from the client to the server, it is good practice to prefix the event name with the app ID or other namespaces to avoid conflicts with other apps or other integrations that may be listening for messages.

`on()`

Signature: on<T>(event: string, callback: (data: T) => void) => void

Registers a callback to be called when the server sends a message with the specified event.

init(canvas, app, server) {
  server.on('server-message', (data) => {
    console.log(data.message);
  });
}

On the server

In your integration’s astro:server:setup hook, you can use the toolbar object to send and receive messages from your apps.

`send()`

Signature: send<T>(event: string, data: T) => void

Sends data to the client

'astro:server:setup': ({ toolbar }) => {
  toolbar.send('server-message', { message: 'Hello!' });
},

`on()`

Signature: on<T>(event: string, callback: (data: T) => void) => void

Registers a callback to be called when the client sends a message with the specified event.

'astro:server:setup': ({ toolbar }) => {
  toolbar.on('my-app:my-message', (data) => {
    console.log(data.message);
  });
},

`onInitialized`

Signature: onInitialized(appId: string, callback: () => void) => void

Registers a callback to be called when the app is initialized.

'astro:server:setup': ({ toolbar }) => {
  toolbar.onInitialized('my-app', () => {
    console.log('The app is now initialized!');
  });
},

`onAppToggled`

Signature: onAppToggled(appId: string, callback: (options: {state: boolean}) => void) => void

Registers a callback to be called when the user clicks on the app icon in the UI to toggle the app on or off.

'astro:server:setup': ({ toolbar }) => {
  toolbar.onAppToggled('my-app', ({ state }) => {
    console.log(`The app is now ${state ? 'enabled' : 'disabled'}!`);
  });
},

Component Library

The Dev Toolbar includes a set of web components that can be used to build apps with a consistent look and feel.

`astro-dev-toolbar-window`

Shows a window.

The slot of the component will be used as the content of the window.

<astro-dev-toolbar-window>
  <p>My content</p>
</astro-dev-toolbar-window>

When building a window using JavaScript, slotted content must go inside the light DOM of the component.

const myWindow = document.createElement('astro-dev-toolbar-window');
const myContent = document.createElement('p');
myContent.textContent = 'My content';

// use appendChild directly on `window`, not `myWindow.shadowRoot`
myWindow.appendChild(myContent);

`astro-dev-toolbar-button`

Shows a button.

The slot of the component will be used as the content of the button.

const myButton = document.createElement('astro-dev-toolbar-button');
myButton.textContent = 'Click me!';
myButton.buttonStyle = "purple";
myButton.size = "medium";

myButton.addEventListener('click', () => {
  console.log('Clicked!');
});

`size`

The size of the button (small, medium, large).

`button-style`

The style of the button (ghost, outline, purple, gray, red, green, yellow, blue). When using ghost, the button itself is invisible and only the content of the button will be shown.

In JavaScript, set this property using the buttonStyle property to avoid conflict with the native style property.

`astro-dev-toolbar-badge`

Shows a badge.

The slot of the component will be used as the content of the badge.

<astro-dev-toolbar-badge>My badge</astro-dev-toolbar-badge>

`size`

The size of the badge (small, large).

`badge-style`

The style (color) of the badge (purple, gray, red, green, yellow, blue).

In JavaScript, set this property using the badgeStyle property to avoid conflict with the native style property.

`astro-dev-toolbar-card`

Shows a card. Specify an optional link attribute to make the card act like an <a> element.

When making a card using JavaScript, a clickAction property can be specified to make the card act like a <button> element.

The slot of the component will be used as the content of the card.

<astro-dev-toolbar-card icon="astro:logo" link="https://github.com/withastro/astro/issues/new/choose">Report an issue</astro-dev-toolbar-card>

`card-style`

The style of the card (purple, gray, red, green, yellow, blue). The color is only applied to the border of the card on hover.

In JavaScript, set this property using the cardStyle.

`astro-dev-toolbar-toggle`

Shows a toggle element, acting as a checkbox. This element internally is a simple wrapper around a native <input type="checkbox"> element. The checkbox element can be accessed using the input property.

const toggle = document.createElement('astro-dev-toolbar-toggle');

toggle.input.addEventListener('change', (evt) => {
  console.log(`The toggle is now ${evt.currentTarget.checked ? 'enabled' : 'disabled'}!`);
});

`toggle-style`

The style of the toggle (purple, gray, red, green, yellow, blue).

In JavaScript, set this property using the toggleStyle property.

`astro-dev-toolbar-highlight`

Can be used to highlight an element on the page. In most cases, you’ll want to position and resize this element using the top, left, width and height CSS properties to match the element you want to highlight.

<!-- Highlight the entire page -->
<astro-dev-toolbar-highlight style="top: 0; left: 0; width: 100%; height: 100%;"></astro-dev-toolbar-highlight>

const elementToHighlight = document.querySelector('h1');
const rect = elementToHighlight.getBoundingClientRect();

const highlight = document.createElement('astro-dev-toolbar-highlight');

highlight.style.top = `${Math.max(rect.top + window.scrollY - 10, 0)}px`;
highlight.style.left = `${Math.max(rect.left + window.scrollX - 10, 0)}px`;
highlight.style.width = `${rect.width + 15}px`;
highlight.style.height = `${rect.height + 15}px`;
highlight.icon = 'astro:logo';

`style`

The style of the highlight (purple, gray, red, green, yellow, blue).

`icon`

An icon to show in the top right corner of the highlight.

`astro-dev-toolbar-tooltip`

Shows a tooltip with different sections. This component is set to display: none; by default and can be made visible using a data-show="true" attribute.

Sections are defined using the sections property. This property is an array of objects with the following shape:

{
  title?: string; // Title of the section
  inlineTitle?: string; // Title of the section, shown inline next to the title
  icon?: Icon; // Icon of the section
  content?: string; // Content of the section
  clickAction?: () => void | Promise<void>; // Action to perform when clicking on the section
  clickDescription?: string; // Description of the action to perform when clicking on the section
}

const tooltip = document.createElement('astro-dev-toolbar-tooltip');

tooltip.sections = [{
  title: 'My section',
  icon: 'astro:logo',
  content: 'My content',
  clickAction: () => {
    console.log('Clicked!')
  },
  clickDescription: 'Click me!'
}]

This component is often combined with the astro-dev-toolbar-highlight component to show a tooltip when hovering a highlighted element:

const highlight = document.createElement('astro-dev-toolbar-highlight');

// Position the highlight...

const tooltip = document.createElement('astro-dev-toolbar-tooltip');

// Add sections to the tooltip...

highlight.addEventListener('mouseover', () => {
  tooltip.dataset.show = 'true';
});

highlight.addEventListener('mouseout', () => {
  tooltip.dataset.show = 'false';
});

`astro-dev-toolbar-icon`

Shows an icon. An icon from the icon list can be specified using the icon attribute, or the SVG markup of an icon can be passed as a slot.

<astro-dev-toolbar-icon icon="astro:logo" />

<astro-dev-toolbar-icon>
  <svg>...</svg>
</astro-dev-toolbar-icon>

Icons

Currently, the following icons are available and can be used in any component that accepts an icon:

astro:logo
warning
arrow-down
bug
file-search
check-circle
gear
lightbulb
checkmark
dots-three
copy

All of the above icons have fill="currentColor" set by default and will inherit their color from the parent element.

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Dev Toolbar App API

Adding apps

`id`

`name`

`icon`

`entrypoint`

`init()`

`canvas`

`app`

`server`

`beforeTogglingOff()`

canvas

Client-side Events

`onToggled()`

`onToolbarPlacementUpdated()`

`toggleState()`

`toggleNotification()`

`state: boolean`

`level: 'error' | 'warning' | 'info'`

Client-Server Communication

On the client

`send()`

`on()`

On the server

`send()`

`on()`

`onInitialized`

`onAppToggled`

Component Library

`size`

`button-style`

`size`

`badge-style`

`card-style`

`toggle-style`

`style`

`icon`

Icons

Dev Toolbar App API

Adding apps

id

name

icon

entrypoint

Structure of a Dev Toolbar App

init()

canvas

app

server

beforeTogglingOff()

canvas

Client-side Events

onToggled()

onToolbarPlacementUpdated()

toggleState()

toggleNotification()

state: boolean

level: 'error' | 'warning' | 'info'

Client-Server Communication

On the client

send()

on()

On the server

send()

on()

onInitialized

onAppToggled

Component Library

astro-dev-toolbar-window

astro-dev-toolbar-button

size

button-style

astro-dev-toolbar-badge

size

badge-style

astro-dev-toolbar-card

card-style

astro-dev-toolbar-toggle

toggle-style

astro-dev-toolbar-highlight

style

icon

astro-dev-toolbar-tooltip

astro-dev-toolbar-icon

Icons

`id`

`name`

`icon`

`entrypoint`

`init()`

`canvas`

`app`

`server`

`beforeTogglingOff()`

`onToggled()`

`onToolbarPlacementUpdated()`

`toggleState()`

`toggleNotification()`

`state: boolean`

`level: 'error' | 'warning' | 'info'`

`send()`

`on()`

`send()`

`on()`

`onInitialized`

`onAppToggled`

`astro-dev-toolbar-window`

`astro-dev-toolbar-button`

`size`

`button-style`

`astro-dev-toolbar-badge`

`size`

`badge-style`

`astro-dev-toolbar-card`

`card-style`

`astro-dev-toolbar-toggle`

`toggle-style`

`astro-dev-toolbar-highlight`

`style`

`icon`

`astro-dev-toolbar-tooltip`

`astro-dev-toolbar-icon`